A species which flights at dawn and dusk is the woodcock, and the ability this bird has to tell the time has long intrigued me.
Flighting woodcock has been written about by many, but I don’t recall ever having seen reference to the accuracy of their internal clocks. Unlike wildfowl, woodcock seem to have internal clocks with Rolex mechanisms. Another observation I have made is that they are apparently not fooled by a false dusk, that is when thick cloud drops light levels to near darkness. They rarely flight, but wait until the time is right.
In order to prove my theory, some three years ago I decided to attempt to quantify the ‘woodcock clock’ by recording the flight times and number of birds seen. While not exactly a scientific survey, the data I collected, though not extensive, bore out my expectations. To record the flight times, I always went to the same spot at the edge of a forestry plantation, and made my observations looking towards the set or setting sun. Initially, I recorded only the time after sunset, when I saw the first and last woodcock flight out, but latterly I have also made notes of the cloud cover, visibility and brightness of the moon and other such factors.
The earliest flight after sunset
I was always in position 20 minutes after sunset (I have never seen woodcock flight earlier than this unless disturbed by something) and left when it was too dark to see anything. It could be said that woodcock flight after I have given up and it was dark but, having developed an innate ability to see wildfowl as vague silhouettes in poor light, I am convinced that few if any woodcock actually flight out from their place of roost during darkness.
In all weather and light conditions, the earliest flight, or the first bird I observed on any given day, was 29 minutes after sunset, and the latest first bird observed on any given day was 42 minutes after sunset, so all first birds flighted in a 13-minute time frame. The earliest I recorded the last bird flighting was 38 minutes after sunset and the latest last bird was 52 minutes after sunset, so all last-seen birds flighted in a 14-minute time frame. To me, this is extraordinary timekeeping, and it was confirmed by the fact that the maximum time interval between the first and last woodcock to flight was 17 minutes, but generally the flight was completed in less than 15 minutes. So who needs a Rolex when you could have a ‘woodcock clock’.